I was adopted- did they take off my birth parents name and where i was born and put something different?

I want to visit my birthdad in prison but they wont let me unless i can prove im his daughter- i either have to get my birth certificate(if they changed the names then i have to go to the city i was adopted in-2hrs away!) or get a notarized letter- i want to see him as soon as i can- any advice?